The average custodian salary at Napa County was $101,955 , which is 40 percent higher than the average salary for this job in California, and 44 percent higher than the national average for this job . Custodian salaries at Napa County typically range from $94,896 to $110,861 (25th to 75th percentile). The highest reported custodian salary was $119,120. There are 15 employees at Napa County with the job title custodian.